Materials Literature
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The degradation of tin-doped indium-oxide (ITO) films in glow-discharge plasmas of hydrogen and argon have been investigated. Parameters which have been varied for the study include the temperature of ITO under ion bombardment, the rf power density, the time of exposure to plasma, and the gas flow rate. After bombardm…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTransition of linear polymer dimensions from .THETA. to collapsed regime. 1. Polystyrene/cyclohexane systemI. H. Park, Q. W. Wang, and Benjamin ChuCite this: Macromolecules 1987, 20, 8, 1965–1975Publication Date (Print):August 1, 1987Publication History Published online1 May…
Solutions of tetramethoxysilicon were reacted, using both acid and base as catalysts, until near the sol-gel transition. Portions of the reacting mixture were quenched by dilution, and the average cluster mass and correlation length were measured with use of static and dynamic light scattering. Critical exponents desc…
Arginine 179 of the alpha subunit of tryptophan synthase of Salmonella typhimurium was changed to leucine by site-directed mutagenesis. The mutant alpha subunit was expressed in S. typhimurium, purified and crystallized as the alpha 2 beta 2 complex, and characterized by kinetic studies under steady-state reaction con…
Abstract Crystal structure of uncomplexed γ-cyclodextrin, C48H80O40·14.1H2O, was determined by the X-ray method. The crystal is monoclinic and the space group is P21 with cell dimensions; a=16.847(2), b=11.098(2), c=20.271(2) Å, and β=104.97(1)°. The structure was solved by the inspection of a Patterson map and the R-…
The dielectric properties of liquid water are studied using an empirical potential model treating the monomers as flexible molecules with short-range interactions between oxygens and Coulomb interactions between charges situated on the individual atoms. Satisfactory results for the static dielectric constants at 259,…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermal stability and kinetic lability of the metal carbonyl bond. A theoretical study on M(CO)6 (M = chromium, molybdenum, tungsten), M(CO)5 (M = iron, ruthenium, osmium), and M(CO)4 (M = nickel, palladium, platinum)Tom Ziegler, Vincenzo Tschinke, and Charles UrsenbachCite…
Abstract A rheological technique is proposed for determining the thermally induced order–disorder transition of block copolymers. In the present investigation, a cone‐and‐plate rheometer was used to measure dynamic storage and loss moduli, G ′(ω) and G ″(ω), as a function of angular frequency ω of a commercial grade p…
Point-contact transistors and Schottky diodes have been formed on synthetic boron-doped diamond. This is the first report of diamond transistors that have power gain. Further, the transistors exhibited power gain at 510°C and the Schottky diodes were operational at 700°C.
The efficiency of a Lyot stop in reducing diffraction effects in a simple optical system is analyzed. The transformation rules of Fourier optics are used to follow the optical signal through the system. This analysis reduces the problem to the evaluation of a two-dimensional integral. An approximate analytic technique…
Abstract The optical properties of bisphenol‐A polycarbonate resin as described by the complex index of refraction, N = n – ik , are derived by Kramers‐Kronig analysis of experimental absorption and reflectance data obtained in the range 40μm ≥ λ ≥ 105 nm. Electronic absorption processes in polycarbonate are character…
In Escherichia coli strains overproducing dinucleoside tetraphosphate hydrolase, the accumulation of dinucleoside tetraphosphates (AppppN, with N = A, C, G, or U) during heat shock or H2O2 treatment was reduced about 10-fold as compared with a control strain. This accumulation neither modified the pattern of the prote…
Solid solutions of AlVO 4 crystallize at lower temperatures than amorphous materials between 50 and 70 mol% Al 2 O 3 prepared by the simultaneous hydrolysis of aluminum and vanadyl alkoxides. They decompose into α‐Al 2 O 3 , and V 2 O 5 , at 775° to 800°C. The compound AlVO 4 prepared from 50 mol% Al 2 O 3 has a tricl…
Abstract The mechanism and rate limitations in aqueous nitrogen oxides absorption are reviewed and data available on chemical kinetics for performance predictions are discussed. Application of a rate relationship to characterize interphase mass transfer for the primary reactant N 2 O 4 is shown, with mass transfer coe…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMagnetic-field effects in the low-temperature polarized emission and absorption spectra of single-crystal tris(2,2'-bipyridine)ruthenium(2+) bis(hexafluorophosphate) ([Ru(bpy)3](PF6)2)Erich Gallhuber, Gerold Hensler, and Hartmut YersinCite this: J. Am. Chem. Soc. 1987, 109,…
To investigate magnetic hardening mechanisms in sintered Nd-Fe-B magnets, magnetic hysteresis loops of sintered Nd 15 Fe 77 B 8 magnets 100 µm thick, the surfaces of which are sputter-deposited with Nd or Tb metal, were measured at various steps in the sample preparation procedures. The surface grains in as-polished m…
Diagrammatic valence bond calculations are applied to the study of the charge–transfer (CT) excitation spectrum and of the electron–molecular vibration (emv) coupling in mixed regular stack CT crystals. The intersite electrostatic interactions are treated by both mean-field and unscreened point–charge potential approa…
Volume crystallization of this glass is nucleated by Li 3 PO 4 . On heating from room temperature, Li 2 SiO 3 appears around 650°C and then converts to Li 2 Si 2 O 5 around 850°C by reaction with SiO 2 from the melt. Preheating the glass at 1000°C forms larger Li 3 PO 4 nuclei that promote additional crystallization o…
A commercial lithium aluminosilicate glass‐ceramic material is investigated by high‐resolution transmission electron microscopy after different heat treatments. Evidence is presented that epitaxy of β‐quartz crystals on ZrTiO 4 ‐type crystallites is the critical step initiating silicate crystallization.
Recently the problem of the glass transition has been further complicated by the discovery of a phase which forms under conditions similar to those required by the formation of metallic glasses. This new phase (the “quasicrystal”) seems to be structurally intermediate between the glass and the crystal phase, being cha…